1 /* 2 * i2c-nforce2-s4985.c - i2c-nforce2 extras for the Tyan S4985 motherboard 3 * 4 * Copyright (C) 2008 Jean Delvare <khali@linux-fr.org> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 19 */ 20 21 /* 22 * We select the channels by sending commands to the Philips 23 * PCA9556 chip at I2C address 0x18. The main adapter is used for 24 * the non-multiplexed part of the bus, and 4 virtual adapters 25 * are defined for the multiplexed addresses: 0x50-0x53 (memory 26 * module EEPROM) located on channels 1-4. We define one virtual 27 * adapter per CPU, which corresponds to one multiplexed channel: 28 * CPU0: virtual adapter 1, channel 1 29 * CPU1: virtual adapter 2, channel 2 30 * CPU2: virtual adapter 3, channel 3 31 * CPU3: virtual adapter 4, channel 4 32 */ 33 34 #include <linux/module.h> 35 #include <linux/kernel.h> 36 #include <linux/slab.h> 37 #include <linux/init.h> 38 #include <linux/i2c.h> 39 #include <linux/mutex.h> 40 41 extern struct i2c_adapter *nforce2_smbus; 42 43 static struct i2c_adapter *s4985_adapter; 44 static struct i2c_algorithm *s4985_algo; 45 46 /* Wrapper access functions for multiplexed SMBus */ 47 static DEFINE_MUTEX(nforce2_lock); 48 49 static s32 nforce2_access_virt0(struct i2c_adapter *adap, u16 addr, 50 unsigned short flags, char read_write, 51 u8 command, int size, 52 union i2c_smbus_data *data) 53 { 54 int error; 55 56 /* We exclude the multiplexed addresses */ 57 if ((addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30 58 || addr == 0x18) 59 return -ENXIO; 60 61 mutex_lock(&nforce2_lock); 62 error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write, 63 command, size, data); 64 mutex_unlock(&nforce2_lock); 65 66 return error; 67 } 68 69 /* We remember the last used channels combination so as to only switch 70 channels when it is really needed. This greatly reduces the SMBus 71 overhead, but also assumes that nobody will be writing to the PCA9556 72 in our back. */ 73 static u8 last_channels; 74 75 static inline s32 nforce2_access_channel(struct i2c_adapter *adap, u16 addr, 76 unsigned short flags, char read_write, 77 u8 command, int size, 78 union i2c_smbus_data *data, 79 u8 channels) 80 { 81 int error; 82 83 /* We exclude the non-multiplexed addresses */ 84 if ((addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30) 85 return -ENXIO; 86 87 mutex_lock(&nforce2_lock); 88 if (last_channels != channels) { 89 union i2c_smbus_data mplxdata; 90 mplxdata.byte = channels; 91 92 error = nforce2_smbus->algo->smbus_xfer(adap, 0x18, 0, 93 I2C_SMBUS_WRITE, 0x01, 94 I2C_SMBUS_BYTE_DATA, 95 &mplxdata); 96 if (error) 97 goto UNLOCK; 98 last_channels = channels; 99 } 100 error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write, 101 command, size, data); 102 103 UNLOCK: 104 mutex_unlock(&nforce2_lock); 105 return error; 106 } 107 108 static s32 nforce2_access_virt1(struct i2c_adapter *adap, u16 addr, 109 unsigned short flags, char read_write, 110 u8 command, int size, 111 union i2c_smbus_data *data) 112 { 113 /* CPU0: channel 1 enabled */ 114 return nforce2_access_channel(adap, addr, flags, read_write, command, 115 size, data, 0x02); 116 } 117 118 static s32 nforce2_access_virt2(struct i2c_adapter *adap, u16 addr, 119 unsigned short flags, char read_write, 120 u8 command, int size, 121 union i2c_smbus_data *data) 122 { 123 /* CPU1: channel 2 enabled */ 124 return nforce2_access_channel(adap, addr, flags, read_write, command, 125 size, data, 0x04); 126 } 127 128 static s32 nforce2_access_virt3(struct i2c_adapter *adap, u16 addr, 129 unsigned short flags, char read_write, 130 u8 command, int size, 131 union i2c_smbus_data *data) 132 { 133 /* CPU2: channel 3 enabled */ 134 return nforce2_access_channel(adap, addr, flags, read_write, command, 135 size, data, 0x08); 136 } 137 138 static s32 nforce2_access_virt4(struct i2c_adapter *adap, u16 addr, 139 unsigned short flags, char read_write, 140 u8 command, int size, 141 union i2c_smbus_data *data) 142 { 143 /* CPU3: channel 4 enabled */ 144 return nforce2_access_channel(adap, addr, flags, read_write, command, 145 size, data, 0x10); 146 } 147 148 static int __init nforce2_s4985_init(void) 149 { 150 int i, error; 151 union i2c_smbus_data ioconfig; 152 153 /* Configure the PCA9556 multiplexer */ 154 ioconfig.byte = 0x00; /* All I/O to output mode */ 155 error = i2c_smbus_xfer(nforce2_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03, 156 I2C_SMBUS_BYTE_DATA, &ioconfig); 157 if (error) { 158 dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n"); 159 error = -EIO; 160 goto ERROR0; 161 } 162 163 /* Unregister physical bus */ 164 if (!nforce2_smbus) 165 return -ENODEV; 166 error = i2c_del_adapter(nforce2_smbus); 167 if (error) { 168 dev_err(&nforce2_smbus->dev, "Physical bus removal failed\n"); 169 goto ERROR0; 170 } 171 172 printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4985\n"); 173 /* Define the 5 virtual adapters and algorithms structures */ 174 s4985_adapter = kzalloc(5 * sizeof(struct i2c_adapter), GFP_KERNEL); 175 if (!s4985_adapter) { 176 error = -ENOMEM; 177 goto ERROR1; 178 } 179 s4985_algo = kzalloc(5 * sizeof(struct i2c_algorithm), GFP_KERNEL); 180 if (!s4985_algo) { 181 error = -ENOMEM; 182 goto ERROR2; 183 } 184 185 /* Fill in the new structures */ 186 s4985_algo[0] = *(nforce2_smbus->algo); 187 s4985_algo[0].smbus_xfer = nforce2_access_virt0; 188 s4985_adapter[0] = *nforce2_smbus; 189 s4985_adapter[0].algo = s4985_algo; 190 s4985_adapter[0].dev.parent = nforce2_smbus->dev.parent; 191 for (i = 1; i < 5; i++) { 192 s4985_algo[i] = *(nforce2_smbus->algo); 193 s4985_adapter[i] = *nforce2_smbus; 194 snprintf(s4985_adapter[i].name, sizeof(s4985_adapter[i].name), 195 "SMBus nForce2 adapter (CPU%d)", i - 1); 196 s4985_adapter[i].algo = s4985_algo + i; 197 s4985_adapter[i].dev.parent = nforce2_smbus->dev.parent; 198 } 199 s4985_algo[1].smbus_xfer = nforce2_access_virt1; 200 s4985_algo[2].smbus_xfer = nforce2_access_virt2; 201 s4985_algo[3].smbus_xfer = nforce2_access_virt3; 202 s4985_algo[4].smbus_xfer = nforce2_access_virt4; 203 204 /* Register virtual adapters */ 205 for (i = 0; i < 5; i++) { 206 error = i2c_add_adapter(s4985_adapter + i); 207 if (error) { 208 printk(KERN_ERR "i2c-nforce2-s4985: " 209 "Virtual adapter %d registration " 210 "failed, module not inserted\n", i); 211 for (i--; i >= 0; i--) 212 i2c_del_adapter(s4985_adapter + i); 213 goto ERROR3; 214 } 215 } 216 217 return 0; 218 219 ERROR3: 220 kfree(s4985_algo); 221 s4985_algo = NULL; 222 ERROR2: 223 kfree(s4985_adapter); 224 s4985_adapter = NULL; 225 ERROR1: 226 /* Restore physical bus */ 227 i2c_add_adapter(nforce2_smbus); 228 ERROR0: 229 return error; 230 } 231 232 static void __exit nforce2_s4985_exit(void) 233 { 234 if (s4985_adapter) { 235 int i; 236 237 for (i = 0; i < 5; i++) 238 i2c_del_adapter(s4985_adapter+i); 239 kfree(s4985_adapter); 240 s4985_adapter = NULL; 241 } 242 kfree(s4985_algo); 243 s4985_algo = NULL; 244 245 /* Restore physical bus */ 246 if (i2c_add_adapter(nforce2_smbus)) 247 printk(KERN_ERR "i2c-nforce2-s4985: " 248 "Physical bus restoration failed\n"); 249 } 250 251 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>"); 252 MODULE_DESCRIPTION("S4985 SMBus multiplexing"); 253 MODULE_LICENSE("GPL"); 254 255 module_init(nforce2_s4985_init); 256 module_exit(nforce2_s4985_exit); 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